Methane decomposition over Ni supported on palm oil fuel ash (Ni-POFA) catalyst.

[Display omitted] • The catalytic performance of Ni-POFA catalyst for methane decomposition has been evaluated. • Increasing the Ni loading from 5 to 15 wt.% increased the Ni-POFA performance. • Catalyst degradation at 20 wt.% Ni loading was due to Ni agglomeration and large filamentous carbon. • Increasing the GHSV from 5000 to 7000 mL/g h increased the Ni-POFA performance. • Low performance at 15,000 and 25,000 mL/g h was due to short contact time between CH 4 gas and Ni-POFA. The performance of Ni supported on palm oil fuel ash (Ni-POFA) catalyst was evaluated for methane decomposition reaction. The effects of Ni loading (5, 10, 15 and 20 wt.%) and gas hourly space velocity (GHSV) (5000, 7000, 15,000 and 25,000 mL/g h) were investigated at 550 °C for 6 h. The results show that increasing the Ni loading from 5 to 15 wt.% increased the initial H 2 yield. However, the highest Ni loading (20 wt.% Ni) resulted in the lowest CH 4 conversion and H 2 yield, which has been associated to Ni particles agglomeration and formation of large filamentous carbon. The increase of GHSV from 5000 to 7000 mL/g h increased the initial CH 4 conversion and initial H 2 yield. Nonetheless, the catalytic performance of Ni-POFA degraded rapidly at higher GHSVs (15,000 and 25,000 mL/g h). This has been linked to a shorter contact time between CH 4 gas and the catalyst at higher CH 4 flow rates. The current study proposes the 15 wt.% Ni and 7000 mL/g h as the optimum Ni loading and GHSV for Ni-POFA catalyst, respectively. Under these conditions, methane decomposition performed admirably at 87.0% initial CH 4 conversion and 27.0% initial H 2 yield. Under the same conditions, the highest stable value of H 2 production was achieved at ∼2.0% over the 6-h reaction time. [ABSTRACT FROM AUTHOR]